Heretofore, it has been well known to provide tire constrictors for mounting large bias ply tires on large equipment or heavy machinery such as construction, military and aircraft tires. Such tires are frequently tubeless and, because of their large size, are extremely heavy and difficult to handle and particularly difficult to mount on a wheel and inflate. The construction of these tires renders them extremely stiff and relatively inflexible. Normally such tires are mountable on wheels having one fixed rim and one removable rim, wherein the removable rim is detached to allow the tire to be first placed on the wheel. The removable rim is then reattached. The general problem is that when the tire is first mounted on the wheel, the beads of the tire are not in contact with the wheel rims, and since the tire is tubeless, the tire cannot be inflated.
One tire constricting device for properly mounting a tire on a wheel includes a flexible strap or belt which is tightened around the circumference of a tire by a fluid powered ram which squeezes the tire along a central plane, thus spreading the beads. This type of mechanism heretofore known is disclosed in U.S. Pat. No. 3,710,837. Other heretofore known devices are described therein.
The mechanism disclosed in U.S. Pat. No. 3,710,837 involves a single flexible strap or belt that is attached at both ends to a box which contains a fluid powered ram for tightening the strap or belt about the tire and thus squeezing the tire along a central plane spreading the beads toward and into engagement with the wheel rims. While this device performs its intended function, it has several problems.
The first problem is that the box and ram can only be used with one width of strap or belt. However, the tubeless tires come in a variety of sizes and plys requiring straps or belts of differing widths. These tires may be as large as 9 feet in diameter and 3 feet in width and range from 2-30 ply construction. For mounting all tires of such varying size, ply, and construction, it is necessary to use wide belts on 2 to 12 ply tires to avoid distorting the casings and narrow belts on 14-30 ply tires. That means two separate conventional tire constrictors are required, one with a small, two-inch wide strap or belt, and one with a large, six-inch wide strap or belt. Accordingly, since two different constrictors are necessary to handle the wide range of tires, the overall expense is double.
The second problem is that the box and ram construction consists of approximately twenty-eight separate pieces of tubing, flat bar, and round bar in each unit, as well as approximately a dozen lock rings, nuts and bolts. The welding of these pieces requires 5 feet or more of MIG weld and a considerable amount of labor. Moreover, the assembly of these pieces also requires a considerable amount of cutting, grinding, and cleaning. This has made tire constrictors high labor input products and has increased their overall cost.
The third problem is that the box and ram construction is susceptible to corrosion in the field. This corrosion is due to the construction of the box which prohibits the painting of the entire unit, specifically inside the tubes which comprise the frame of the box. This corrosion leads to weakening of the device and reduces the useful life of the tire constrictor. This increases the overall maintenance expense to the user.